1. Field of the Invention
The present invention relates to a lamp unit for a vehicle, and more particularly to a lamp unit for a vehicle which is disposed in each of front or rear corner portions.
2. Related Art
Hitherto, each of lamp units for a vehicle, such as clearance lamps, turn signal lamps and hazard lamps, which are disposed in front or rear corner portions of a vehicle, has a structure, for example, as shown in FIG. 5.
FIG. 5 shows a turn signal lamp comprising a case-shape lamp body 1 incorporating therein a reflector 2 having an aluminum-evaporated inner surface and formed integrally with the lamp body 1, a bulb 3 received by a bulb insertion hole la formed in the lamp body 1 and a front lens 4 joined to a front opening portion of the lamp body 1.
Reference numeral 5 represents an amber color cap mounted to cover the bulb 3 so that light emitted from the bulb 3 is changed to amber.
When the bulb 3 has been turned on, light is mainly reflected by the reflector 2. Then, light emits forward through the lens 4, as indicated with an arrow shown in FIG. 5. On the other hand, a portion of light is not reflected by the reflector 2. The portion of light directly emits toward the front through the front lens 4. Thus, the visibility from front portions can be improved.
Moreover, the above-mentioned structure is arranged in such a manner that the outer portion of the color cap 5 is subjected to a lens cutting process or the like in order to improve a light diffusion characteristic to the side portions.
The above-mentioned structure has the arrangement that the bulb insertion hole 1a opened in the direction of the axis of the vehicle is formed at substantially a central portion in the horizontal direction of the lamp body 1 (the reflector 2). Moreover, the bulb 3 is longitudinally disposed (mounted in parallel to the direction of the axis of the vehicle). Therefore, the rear portion of the bulb 3 of the reflector 2 is not effective to reflect Light. Thus, the area of the effective reflecting surface of the reflector 2 is reduced. As a result, there arises a problem in that the quantity of light obtainable from the lamp is unsatisfactorily small. It is a known fact that the obtainable quantity of light is determined by the size of the lamp body 1 (the reflector 2). Therefore, the above-mentioned tendency becomes more critical as the size of the lamp body is reduced.
The above-mentioned structure is arranged such that the color cap 5 is subjected to the lens cutting process or the like to enlarge the quantity of light which can emit sidewardly. The diffusion effect realized by the lens cutting process causes only direct light emitted by the bulb to be diffused. Therefore, the overall quantity of the reflecting-type lamp having the reflector which realizes a required quantity cannot be enlarged.